WO2016066298A1 - Procédé permettant l'estimation de la capacité calorifique de denrées alimentaires - Google Patents

Procédé permettant l'estimation de la capacité calorifique de denrées alimentaires Download PDF

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Publication number
WO2016066298A1
WO2016066298A1 PCT/EP2015/069276 EP2015069276W WO2016066298A1 WO 2016066298 A1 WO2016066298 A1 WO 2016066298A1 EP 2015069276 W EP2015069276 W EP 2015069276W WO 2016066298 A1 WO2016066298 A1 WO 2016066298A1
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Prior art keywords
temperature
refrigerated volume
refrigerated
air inside
air
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PCT/EP2015/069276
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English (en)
Inventor
Seyed Ehsan Shafiei
Roozbeh Izadi-Zamanabadi
Original Assignee
Danfoss A/S
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Publication date
Application filed by Danfoss A/S filed Critical Danfoss A/S
Publication of WO2016066298A1 publication Critical patent/WO2016066298A1/fr

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
    • F25D29/00—Arrangement or mounting of control or safety devices
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K7/00—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements
    • G01K7/42—Circuits effecting compensation of thermal inertia; Circuits for predicting the stationary value of a temperature
    • G01K7/427—Temperature calculation based on spatial modeling, e.g. spatial inter- or extrapolation
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2500/00—Problems to be solved
    • F25B2500/19—Calculation of parameters
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2700/00—Sensing or detecting of parameters; Sensors therefor
    • F25B2700/21—Temperatures
    • F25B2700/2106—Temperatures of fresh outdoor air
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
    • F25D2700/00—Means for sensing or measuring; Sensors therefor
    • F25D2700/16—Sensors measuring the temperature of products

Definitions

  • the present i nvention relates to a method for estimating a thermal capacity of foodstuff stored in a refrigerated volu me of a refrigeration system, and for control ling the refrigeration system, based on the estimated thermal capacity of the foodstuff.
  • a re stored in a refrigerated volume such as a display case in a supermarket
  • the air temperature inside the refrigerated volume is normally measured, a nd a refrigeration system is controlled i n such a man ner that the air temperature is maintained within an acceptable temperatu re range.
  • the air temperature inside the refrigerated volume is not necessarily the same as the temperature of the stored goods.
  • the temperature of the stored goods may very wel l be maintained within an acceptable tem perature ra nge, even if the air temperatu re inside the refrigerated volu me is allowed to exceed the boundaries of the acceptable temperature ra nge for a short period of time.
  • This may, e.g ., be used if it is desired to use the stored goods for energy storage, or if it is desired to implement cooling down of new goods being added to the refrigerated volu me in an energy efficient manner. It may therefore be desirable to obtain knowledge rega rding thermal dyna mics of the foodstuff being stored .
  • US 7,596,432 B2 discloses a method for controlling the temperature i nside a cavity of a cooling appliance provided with a temperature sensor inside the cavity and with actuator means, such as a compressor, a da mper and/or a fan, for adjusting the cooli ng capacity of the applia nce.
  • the food temperature is estimated on the basis of the va lue from the temperature sensor a nd on a predetermined function of the status of the actuator means.
  • US 6,471,398 B2 discloses a temperature management apparatus for foodstuffs stored in a storage cabinet, wherein a temperatu re sensor is placed i n the storage cabinet to detect an inside temperature of the cabinet, thereby to calculate a n a mbient temperature of the foodstuffs, based on the detected inside temperature.
  • An internal temperature of the foodstuffs is presumed on a basis of the ca lculated ambient temperature .
  • the invention provides a method for estimating a thermal ca pacity of foodstuff stored in a refrigerated volu me of a refrigeration system, the refrigeration system comprising a compressor u nit, a condenser unit, an expansion valve a nd a n evaporator, arranged in a refrigerant path, the eva porator being a rranged in thermal contact with the refrigerated volume, and the expa nsion valve being provided in the refrigerant path u pstream of the evaporator, an opening degree of the expa nsion va lve bei ng controlled on the basis of a temperature of air inside the refrigerated volu me and in order to obtain a temperature of the air inside the refrigerated volu me which is equal to a setpoint temperatu re, the method comprising the steps of:
  • the invention relates to a method for estimating a thermal ca pacity of foodstuff stored in a refrigerated volu me of a refrigeration system .
  • the term 'refrigeration system' shou ld be interpreted to mea n a ny system in which a flow of fluid medium, such as refrigerant, circulates and is alternatingly compressed and expa nded, thereby providi ng refrigeration or heating of a volume.
  • the refrigeration system may be a cooling system, a freezer, etc.
  • the refrigeration system comprises a com pressor u nit, comprising one or more compressors, a condenser u nit, comprising one or more condensers or one or more gas coolers, an expansion valve and an evaporator arranged in a refrigerant path.
  • Refrigerant flowing in the refrigerant path is com pressed by the compressors of the compressor unit.
  • the compressed refrigerant is supplied to the condenser unit, where the refrigerant is at least partly condensed, and heat exchange takes place with the am bient i n such a manner that heat is rejected from the refrigera nt flowing through the condensers or gas coolers of the condenser unit.
  • the refrigerant is then supplied to the expansion valve, where the refrigerant is expanded, before being supplied to the evaporator.
  • the refrigera nt being supplied to the evaporator is thereby in a mixed Iiquid and gaseous state .
  • the Iiquid part of the refrigerant is at least pa rtly evaporated, and heat exchange takes place with the ambient in such a man ner that heat is absorbed by the refrigerant flowing through the eva porator.
  • the refrigera nt is once again supplied to the compressor unit.
  • the evaporator is arranged in thermal contact with a refrigerated volume.
  • the refrigerated volu me is cooled, due to the heat excha nge with the refrigerant flowing through the evaporator. Accordingly, cooling is also provided for foodstuff stored i n the refrigerated volume.
  • the expansion valve is provided in the refrigerant path upstream of the evaporator. Thereby the supply of refrigerant to the evaporator is controlled by means of the expansion valve, more particularly by varying an opening degree of the expansion valve.
  • the opening deg ree of the expansion valve, and thereby the supply of refrigerant to the evaporator, is control led on the basis of a temperatu re of air i nside the refrigerated volume and i n order to obtai n a temperature of air inside the refrigerated volume which is equal to a setpoint temperature. Accordingly, it is attempted to control the refrigeration system in such a manner that the foodstuff stored in the refrigerated volume is stored at the setpoint temperature.
  • the temperature of the foodstuff stored in the refrigerated volume is equal to an average temperature of ai r inside the refrigerated volu me.
  • a difference between the temperatu re of the air and the temperature of the foodstuff will exist for a period of ti me, u nti l a new steady state situation has been esta blished, because the thermal capacity of the foodstuff will normally be higher than the thermal capacity of the air.
  • the length of the period of time depends on the difference or ratio between the thermal capacity of the foodstuff and the thermal capacity of the air. Thus, it may sometimes be safe to increase or decrease the temperature of air inside the refrigerated volu me, for a limited period of time, without risking that the temperature of the foodstuff stored in the refrigerated volume is increased or decreased to an unacceptable temperature level .
  • a therma l capacity of air inside the refrigerated volume is initially estimated .
  • the actual physical quantity 'thermal capacity' may be estimated, or another quantity being representative for the thermal capacity may be estimated .
  • This provides a measure for the thermal dynamics of the air inside the refrigerated volu me, i .e. a measu re for how fast the temperatu re of air i nside the refrigerated volume increases or decreases in response to changes in a mbient conditions or operating parameters, such as changes in the su pply of refrigerant to the evaporator.
  • the setpoint temperatu re for the air inside the refrigerated volu me is changed .
  • the opening degree of the expansion valve, and thereby the supply of refrigerant to the evaporator is controlled in order to obtain a temperatu re of the air inside the refrigerated volume, which is equa l to the new setpoint temperature. Accordingly the temperature of air inside the refrigerated volu me is gradua lly changed, i .e. the temperature is either increased or decreased.
  • the air tem peratu re inside the refrigerated volu me is monitored .
  • the expansion va lve is controlled in order to obtain the new setpoint temperature of the ai r i nside the refrigerated volume
  • the cha nge in the temperature of air inside the refrigerated volume depends on the heat transfer between the evaporator and the ai r inside the refrigerated volume, but also on the heat transfer between the foodstuff stored in the refrigerated volume and the air inside the refrigerated volu me.
  • monitoring the air temperature inside the refrigerated volume provides information regarding the thermal capacity of the foodstuff stored i nside the refrigerated volu me, or at least information regarding the relationship between the thermal capacity of the air inside the refrigerated volume and the therma l ca pacity of the foodstuff stored inside the refrigerated volume.
  • a therma l capacity of the foodstuff stored in the refrigerated volu me is esti mated, based on the monitored air temperature inside the refrigerated volume, a nd based on the estimated thermal capacity of the air inside the refrigerated volume.
  • the actual physical qua ntity 'therma l capacity' may be estimated, or another qua ntity being representative for the thermal capacity may be estimated .
  • the refrigeration system is controlled at least pa rtly on the basis of the estimated thermal capacity of the foodstuff stored in the refrigerated volu me.
  • the thermal capacity of the foodstuff stored in the refrigerated volu me is estimated, purely by estimating the thermal capacity of the air inside the refrigerated volume, and by monitoring the temperature of the air inside the refrigerated volume.
  • the thermal capacity of the foodstuff stored in the refrigerated volume can be used for controlling the refrigeration system, while taking the thermal capacity of the foodstuff into account.
  • the refrigeration system may be controlled in such a man ner that the temperature of the air i nside the refrigerated volume is allowed to increase above an upper temperature limit for a limited period of time, where the limited period of time is selected in such a ma nner that the temperature of the foodstuff will not i ncrease above the upper temperature limit during the period of time where the temperature of the air inside the refrigerated volume is al lowed to increase above the upper temperature limit.
  • the temperature of the air inside the refrigerated volume can be increased, thereby saving energy, without risking that the actual tem perature of the foodstuff increases above an acceptable temperature limit, i .e. without affecting the food safety.
  • the step of estimating a thermal ca pacity of air inside the refrigerated volume may comprise determining a time consta nt being representative for therma l dynamics of the air inside the refrigerated volume.
  • the time constant may, e.g. , reflect how fast the temperatu re of the air inside the refrigerated volume changes in response to a cha nge i n temperature of the evaporator and/or other objects being arra nged i n thermal contact with the ai r i nside the refrigerated volu me.
  • the step of estimating a thermal capacity of the foodstuff stored in the refrigerated volume may comprise determining a time constant being representative for thermal dyna mics of the foodstuff stored inside the refrigerated volume.
  • the time constant may, e.g. , reflect how fast the tem perature of the foodstuff changes in response to changes i n the temperature of the air inside the refrigerated volume.
  • the therma l dynamics of the air inside the refrigerated volu me and the thermal dynamics of the foodstuff stored in the refrigerated volume in combination determine the heat transfer between the air i nside the refrigerated volume a nd the foodstuff stored in the refrigerated volume.
  • the step of monitoring the temperature of air i nside the refrigerated volume may com prise determining a time interval elapsing from the setpoint temperature for the air inside the refrigerated volu me is changed until the temperature of air inside the refrigerated volume reaches a predefined temperature level, and the thermal ca pacity of foodstuff stored inside the refrigerated volume may further be estimated based on the determined elapsed time interva l .
  • the temperature of air inside the refrigerated volu me is monitored in order to determine how fast the temperatu re of the ai r responds to the change in setpoint temperatu re, notably how fast a predefined temperature level is reached, following the change in setpoint temperatu re.
  • the change in temperature of air inside the refrigerated volume depends on the thermal dynamics of the foodstuff stored in the refrigerated volume, and on the thermal dyna mics of the air inside the refrigerated volume.
  • the thermal dynamics of the foodstuff stored in the refrigerated volume are fast, the heat tra nsfer between the foodstuff stored in the refrigerated volume and the air inside the refrigerated volu me is high, and the temperatu re of the foodstuff stored in the refrigerated volu me will have a significant effect on the temperature of the air inside the refrigerated volu me. This will slow down the change i n the temperatu re of the air inside the refrigerated volu me, and as a consequence, the time interva l elapsing before the predefined temperature level is reached is therefore relatively long in this case.
  • information regarding the thermal capacity of the foodstuff stored in the refrigerated volume can be derived from the length of the time interval elapsing from the setpoint temperature for the air inside the refrigerated volume is changed until the predefined temperature level is reached.
  • the predefined tem perature level may be a cut-in temperatu re representing an u pper temperature limit of a temperatu re deadband associated with the setpoint temperatu re of the air inside the refrigerated volu me.
  • the refrigeration system When controlling a refrigeration system in order to obtain a temperature of air i nside the refrigerated volu me which is equal to a setpoint temperature, the refrigeration system is often controlled in such a man ner that the temperatu re of the air is kept within a temperature deadba nd with a lower temperatu re limit below the setpoint tem peratu re and an upper temperature limit above the setpoint temperature.
  • the expansion valve is opened in order to decrease the temperature of the air inside the refrigerated volu me . Therefore the u pper temperatu re limit is sometimes referred to as the cut-in temperature.
  • the expansion valve is closed in order to a llow the temperatu re of the air inside the refrigerated volume to increase. Therefore the lower temperatu re limit is sometimes referred to as the cut-out temperatu re.
  • the expansion valve may initially be closed in order to allow the temperature of the air inside the refrigerated volume to increase to the new setpoint temperature.
  • the expa nsion valve is opened, and a normal deadband control of the expansion valve, with respect to the new setpoint, is initiated . Accordingly, the time interval elapsing from the setpoint tem perature was increased unti l the cut-in tem peratu re is reached, provides a suitable measure for how fast the temperature of the air inside the refrigerated volume changes to establish a new 'normal' situation, based on the new setpoint temperature.
  • the step of controlling the refrigeration system at least partly on the basis of the estimated thermal capacity of the foodstuff stored in the refrigerated volu me may further comprise controlling the refrigeration system in accordance with a request for increased or decreased power consum ption by the refrigeration system received from a power grid which the refrigeration system is connected to.
  • a power grid normal ly has a nu mber of power producers and a number of power consumers connected thereto.
  • the total power consumption of the power consu mers may va ry significa ntly, even on a relatively small ti mescale. Some of the power producers may be large power pla nts.
  • the power production of such la rge power plants can not easily be adjusted, i n particula r on a small ti mescale. Therefore it may sometimes be desirable to request some of the power consu mers to adjust their power consumption, in order to match the tota l power production of the power producers and the total power consumption of the power consumers. This is sometimes referred to as a smart grid .
  • the temperature of air inside the refrigerated volu me may be increased in order to reduce the power consumption, or decreased in order to increase the power consumption of the refrigeration system for a limited period of time. However, this may only be done if it is safe with respect to the foodstuff stored in the refrigerated volume .
  • the estimated thermal capacity of the foodstuff stored i n the refrigerated volume can be used for determining how much and for how long the temperature of air inside the refrigerated volu me can be allowed to deviate from the normal setpoint temperature, without risking that the foodstuff stored in the refrigerated volume is damaged.
  • the method of the invention allows the refrigeration system to be used as an active power consumer in a sma rt grid .
  • the step of changi ng a setpoint temperatu re for the air inside the refrigerated volu me may comprise increasing the setpoint temperature.
  • the setpoint tem perature may be decreased .
  • the method may be performed in the following man ner.
  • n the original equation is equal to 1 as the time (3') is the start point of the step change .
  • Equation 18 Dividing both sides of the Equation 18 with corresponding terms in Equation 19 we get:
  • Fig. 1 is a block diagram illustrating a method according to an embodiment of the invention
  • Fig. 2 is a graph illustrating temperature variations in a refrigeration system being controlled in accordance with a method according to an embodiment of the invention
  • Fig. 3 is a flow chart illustrating a method according to an embodiment of the invention.
  • Fig. 1 is a block diagram illustrating a method according to an embodiment of the invention.
  • a temperature setpoint and corresponding cut-in and cut-out temperatures are supplied to a controller 1.
  • the controller 1 then controls an opening degree of an expansion valve, in order to obtain a temperature of air inside a refrigerated volume 2, in the form of a display case, which is within the temperature deadband defined by the cut-in and cut-out temperatures.
  • the expansion valve is arranged in a refrigerant path upstream relative to an evaporator which is a rranged in therma l contact with the refrigerated volume 2, the expansion valve thereby controlling the supply of refrigera nt to the eva porator.
  • the temperature, T air of air inside the refrigerated volume 2 is measured and supplied to a first estimator 3. Based on the measu red air temperatu re, T air , the first estimator 3 estimates a thermal capacity of air i nside the refrigerated volume 2. This includes estimating a time consta nt, x air , which is representative for the therma l dynamics of the air inside the refrigerated volume 2.
  • the time constant, T air may, e .g ., represent how fast the temperature of the air inside the refrigerated volume 2 reacts to changes, such as a change in setpoint temperature for the air inside the refrigerated volume 2.
  • the new setpoint temperature a nd the corresponding new cut-in and cut-out temperatures are supplied to the controller 1, and the controller 1 controls the opening degree of the expansion valve in the manner described above, but in accorda nce with the new setpoint temperature and correspondi ng cut-in and cut-out temperatures.
  • the temperatu re, T air of air inside the refrigerated volume 2 is measured, and the measured air temperatu re, T air , is supplied to a second estimator 4.
  • the time constant being representative for the therma l dynamics of the air inside the refrigerated volume 2, which was estimated by the first estimator 3, is a lso supplied to the second estimator 4.
  • the second estimator 4 estimates a thermal capacity of the foodstuff stored in the refrigerated volume 2. This includes estimating a ti me consta nt, ⁇ food which is representative for the therma l dynamics of the foodstuff stored in the refrigerated volume 2.
  • the time constant may, e .g ., represent how fast the temperature of the foodstuff stored in the refrigerated volume 2 reacts to cha nges, such as changes in the temperatu re of the air inside the refrigerated volu me 2.
  • the ti me consta nt, for the foodstuff may reflect a heat tra nsfer coefficient of the foodstuff stored in the refrigerated volume 2.
  • the estimated time constant, for the foodstuff stored in the refrigerated volu me 2 is output from the second estimator 4, and may, e.g ., be su pplied to a controller used for controlling the refrigeration system .
  • Fig. 2 is a graph illustrating temperature variations in a refrigeration system being controlled in accordance with a method according to an embodiment of the invention .
  • the solid line represents a temperatu re, T air , of air inside a refrigerated volu me as a function of time
  • the dotted line represents a temperatu re, T food , of foodstuff stored in the refrigerated volume as a function of time .
  • the refrigeration system is controlled in accordance with an initial setpoint temperature, T al , and corresponding cut-in temperature, T A2 , and cut-out temperature, T A1 .
  • the refrigeration system is controlled in such a man ner that the temperatu re, T air , of air i nside the refrigerated volume is maintained within the temperature i nterva l from T A1 to T A2 .
  • the temperature, of the foodstuff stored in the refrigerated volu me remains su bsta ntially constant at the initia l setpoint tem perature, T while the temperature, T air , of the air inside the refrigerated volume fluctuates within the allowed temperature deadband, and the system is in a steady state.
  • the temperature, T air of air inside the refrigerated volume is monitored, in order to investigate how the air temperatu re, T air , changes in response to changes in the su pply of refrigerant to the evaporator.
  • the rate of change of the air temperature, T air in various phases of the temperature cycle between the cut-out temperature, T A1 , and the cut-in temperature, T A2 , may be determined .
  • a thermal capacity of the air i nside the refrigerated volu me is derived, e.g . including a time constant, which is representative for the thermal dynamics of the air inside the refrigerated volu me.
  • the setpoint temperature, a nd the corresponding cut-in and cut-out temperatu res are increased to a new, higher level.
  • the new setpoint temperature is illustrated as T a2
  • the new cut-in temperature is illustrated as T A4
  • the new cut-out temperatu re is i llustrated as T A3 .
  • the refrigeration system is subsequently control led in accordance with the new setpoint temperature, T a2 , and the correspondi ng new cut-in temperature, T A4 , a nd cutout temperatu re, T A3 .
  • the new setpoint temperature, T a2 , and corresponding temperature deadband are arranged at a higher temperature level than the i nitial setpoint temperature, T al , and corresponding temperature deadba nd, this causes the tem perature, T air , of air inside the refrigerated volu me to increase.
  • the increased air temperatu re, T air causes the temperature, T food , of the foodstuff stored in the refrigerated volu me to increase . It can be seen in the gra ph of Fig . 2 that the temperatu re, T air , of the air inside the refrigerated volume increases significantly faster than the temperature, T f00d , of the foodstuff stored in the refrigerated volu me.
  • T air Du ring this i ncrease in the temperature, T air , of air i nside the refrigerated volume the air temperature, T air , is monitored. In particu lar it is detected when the new cut-in temperature, T A4 , is reached, and the time i nterval elapsing from the time 5 where the change in setpoint temperature was initiated and the time 6 where the new cut-in temperature, T A4 , is reached, is detected . Based on this, a thermal capacity of the foodstuff stored in the refrigerated volume is derived, e.g. including a time constant, which is representative for the thermal dyna mics of the foodstuff stored in the refrigerated volume.
  • the change i n the temperature, T air , of air inside the refrigerated volume, following the change i n temperature setpoint depends on the heat transfer between the foodstuff stored in the refrigerated volu me and the air inside the refrigerated volu me .
  • T air the temperature of the air inside the refrigerated volu me
  • the colder foodstuff will cool the air inside the refrigerated volu me, due to the heat transfer between the foodstuff and the air, thereby slowing down the increase in the air temperatu re, T air .
  • the length of the time interva l ela psing from the change in temperature setpoint is initiated, at time 5, u ntil the new cut-in temperature, T A4 , is reached, at time 6, provides information regarding the thermal capacity of the foodstuff stored in the refrigerated volu me. It ca n be seen i n Fig . 2 that a new steady state is obtained at the new temperatu re setpoint, T a2 , when the temperature of the foodstuff, T food , has reached this temperature level .
  • Fig. 3 is a flow chart illustrating a method accordi ng to an embodiment of the i nvention .
  • a controller controls an opening degree of an expansion valve in accordance with an initia l temperature setpoint and corresponding cut-in a nd cut-out temperatures, e .g . as described above with reference to Fig . 1 and/or Fig . 2.
  • the temperature of air inside the refrigerated volu me is measu red or monitored, while the expansion valve is closed, i.e. while the opening degree (OD) of the expa nsion valve is zero. This may, e.g ., be from point ( 1) to point (2) in the gra ph of Fig . 2. In particula r, it is measured how the air tem peratu re changes from the cut-out tem peratu re to the cut-in tem peratu re.
  • an esti mate for a time constant, -c air , bei ng representative for thermal dynamics of the air inside the refrigerated volu me is computed, based on the air temperatu re measured at step 8. Thereby a thermal capacity for the air i nside the refrigerated volume is obtained .
  • a temperature setpoint for the air inside the refrigerated volume, and corresponding cut-in and cut-out temperatures, are increased to a higher level.
  • the expansion valve is closed, i.e. the opening degree (OD) of the expansion valve is set to zero, as a consequence of the increased temperature setpoint, and in order to allow the temperature of the air inside the refrigerated volume to increase, thereby allowing the temperature of the air inside the refrigerated volume to reach the new setpoint temperature.
  • the temperature is measured or monitored. This may, e.g., be from point (3) to point (4) in the graph of Fig.2.
  • the length of the time interval elapsing from the temperature setpoint is changed until the cut-in temperature of the new temperature deadband is reached, is detected.
  • the temperature of the air inside the refrigerated volume reaches the cut-in temperature, i.e. the upper temperature limit of the new temperature deadband. This may, e.g., be at point (4) in the graph of Fig.2.
  • the expansion valve is opened fully, i.e. the opening degree (OD) of the expansion valve is set to a maximum value, in order to decrease the temperature of the air inside the refrigerated volume.
  • the maximum opening degree of the expansion valve is maintained until the temperature of the air inside the refrigerated volume reaches the cut-out temperature, i.e. the lower temperature limit of the new temperature deadband. This may, e.g., be at point (5) in the graph of Fig.2.
  • the expansion valve is once again closed, i.e. the opening degree (OD) of the expansion valve is set to zero, because the temperature of the air inside the refrigerated volume has reached the cut-out temperature. Thereby the temperature of the air inside the refrigerated volume starts to increase again towards the cut-in temperature. This may, e.g., be from point (5) to point (6) in the graph of Fig.2. During this, the temperature of the air inside the refrigerated volume is measured or monitored.
  • step 14 the temperature data which was obtained during steps 11 and 13 is used along with a measured indoor temperature, T and the time constant, x air , which was estimated at step 9, for estimating a time constant, being representative for thermal dynamics of the foodstuff stored in the refrigerated volume. Thereby a thermal capacity for the foodstuff stored in the refrigerated volume is obtained.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
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  • General Engineering & Computer Science (AREA)
  • Devices That Are Associated With Refrigeration Equipment (AREA)

Abstract

L'invention concerne un procédé permettant l'estimation d'une capacité calorifique de denrées alimentaires stockées dans un volume réfrigéré d'un système frigorifique. Une capacité calorifique de l'air à l'intérieur du volume réfrigéré est estimée, par exemple une constante de temps. Ensuite, la température de consigne pour l'air à l'intérieur du volume réfrigéré est modifiée et la température de l'air à l'intérieur du volume réfrigéré est suivie. Une capacité calorifique des denrées alimentaires stockées dans le volume réfrigéré, par exemple une constante de temps, est estimée sur la base de la température de l'air suivie et de la capacité calorifique estimée de l'air à l'intérieur du volume réfrigéré. Le système frigorifique est régulé au moins en partie sur la base de l'estimation de la capacité calorifique des denrées alimentaires stockées dans le volume réfrigéré.
PCT/EP2015/069276 2014-10-27 2015-08-21 Procédé permettant l'estimation de la capacité calorifique de denrées alimentaires WO2016066298A1 (fr)

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CN108688499A (zh) * 2018-05-25 2018-10-23 广汽丰田汽车有限公司 动力电池温度采集电路及系统、电动汽车
JP6725088B1 (ja) 2019-03-19 2020-07-15 ダイキン工業株式会社 設定温度算出装置、低温処理システム、設定温度算出方法及び設定温度算出プログラム
EP3839378A1 (fr) * 2019-12-20 2021-06-23 Danfoss A/S Procédé permettant de commander un système de compression de vapeur pendant un délestage de charge
EP4227603B1 (fr) * 2022-02-11 2024-03-27 Danfoss A/S Procédé de génération d'avertissement de température précoce dans un système de compression de vapeur

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DE102010055903A1 (de) * 2010-10-20 2012-04-26 Liebherr-Hausgeräte Ochsenhausen GmbH System umfassend wenigstens ein Kühl-und/oder Gefriergerät
WO2013007629A2 (fr) * 2011-07-12 2013-01-17 A.P. Møller - Mærsk A/S Régulation de température dans un conteneur de transport réfrigéré

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DE102010055903A1 (de) * 2010-10-20 2012-04-26 Liebherr-Hausgeräte Ochsenhausen GmbH System umfassend wenigstens ein Kühl-und/oder Gefriergerät
WO2013007629A2 (fr) * 2011-07-12 2013-01-17 A.P. Møller - Mærsk A/S Régulation de température dans un conteneur de transport réfrigéré

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